Landing Gear Alignment

[CBogle]

Folks:

I have a '48 170 with the P Ponk mod and solid axles. Today, while taxiing across a grass field between runways, my right gear "bounced" into a pretty good "pothole." The drop into and out of the "pothole" was not terribly extreme, but it wasn't what I would call gentle either. My concern is that I've knocked the gear out of proper alignment. Upon visual inspection of the gear I can't detect any anomoly nor is the gear lose in any way. In addition, I notice no difference when I taxi or take-off or land, such as pulling to the right.

Anyway, my question is, how easy is it to knock these 170 gears out of alignment? I know this is purely a judgement call with no difinitive quantative answer, but, just looking for some experienced feedback. I'm looking for opinions as to whether I need to go through the trouble of having a professional check the alignment or am I just being concerned over something that would not be likely to cause any change in the gear set-up?

Thanks,

Curt
N4288V

[doug8082a]

When I owned 82A I had a few rough landings at first and it never affected the alignment. More significantly, I had one incident where a previous mechanic didn't tie it down properly. The next day we had 50 mph winds and the plane was picked up onto it's right main wheel enough to force the wing tip onto the pavement and push the plane about 6 feet to the right before dropping it back down. Amazingly, it never affected the gear. Four years later and it still tracks true. Never, ever had a problem. All this on stock gear and a stock gear box.

IMHO, the stock gear and gear box is a lot stronger than people give it credit for. It's a lot harder to "knock" the gear out of alignment than people think - particularly on the paved or grass strips that most of us operate on (operations on skis and extreme off-airport strips is another matter entirely). If you just droppped into a pothole and haven't noticed any changes in handling, then my guess is you are probably fine. If the incident imparted a twisting moment on the gear, I might be concerned, but a straight drop in and out is probably more of a shock to the pilot than to the gear itself.

[GAHorn]

Curt, the gear is supported at it's inboard end by a AN7 bolt (a hardened bolt 7/16" diameter about 2" long) which holds it downward upon a machined forging. It's only "weakness" is if the gear leg is forced downward at the wheel-end so as to use it as a lever against the blocks at the lower strut to pry the inboard end upward. This action, if forceful enough (such as might occur in a "hopping" sideways movement or ground-loop) might strip the bolt/nut threads and pull the inboard end of the gearleg upward and towards the cabin floor, as if the outboard/lower end of the gear were being folded beneath the cabin.
It doesn't sound as if that is the stress your gear experienced.
You can make a visual inspection yourself. Lay on your back beneath the airplane and look at the 6-8" wide strip of aluminum which is rivetted onto the belly and runs between the two main gear legs. If that skin is not wrinkled, ... and if the door posts especially in the vicinity of the lower door-hinge and below) is not wrinkled.... if you can attempt to shove the gear leg forward and aft by hand and not detect any movement between the leg and the fuselage... if you can lift the plane off the ground (either by supporting the belly by a cradle, or lifting the fuselage by using a hoist and a strap around the engine mounts, or by jacking the plane at the tie-down rings at the upper end of the struts, a la a Cessna 210, etc..... and if you can then shake the gear legs fore/aft and no movement exists beyond the normal flexing of the main-gear flatsprings, and there's no movement when they are shaken up/down.... then I'd say your airplane is just fine and you shouldn't have cause to worry.
But don't let online help discourage you from having it inspected.

[CBogle]

Guys:

Thank you very much for your helpful and timely responses. I'll do a visual inspection tomorrow as advised, but, it doesn't seem likely that anything is damaged based on your descriptions of the gear construction and the forces encountered.

Every time I have a question regarding my 170, you and other members always help out with information that is right on the money. What a great organization.

Best regards,

Curt

[GAHorn]

I should also have stated that you should pull up your carpet and open the inspection holes below the floor and below the belly, and visually inspect the area for cracks and damage. I'll bet it's fine.

[mrpibb]

Heres a IPC pic of the assy.